Contact for high voltage gas blast circuit breaker with time-delayed opening

ABSTRACT

A pair of contacts for use in a high voltage gas blast circuit interrupter each consists of tubular members having one solid end, with the opposite end of the contacts being segmented to define contact fingers. One contact is fixed and the end of its segmented fingers receive the solid end of the movable contact. The operating shaft for moving the movable contact to the open position is then connected to the movable contact through a spring member to cause a time delay between the initial opening operation of the operating shift and the opening of a blast valve also operated by the operating shaft before the movable contact is snapped to an open position with respect to the stationary contact.

United States Patent mi Kueharski i 1 CONTACT FOR HIGH VOLTAGE GAS BLASTCIRCUIT BREAKER WITH TIME-DELAYED OPENING [75] Inventor: Leonard J.Kucharski. Harleysville.

[73] Assignee: I-T-E Corporation. Spring House.

[22] Filed: Sept. I9, 1973 [Zl] Appl, No.: 398,870

[ June 10, 1975 FOREIGN PATENTS OR APPLICATIONS 6|3.844 l2/l948 UnitedKingdom 200/!48 R Primary ExaminerRobert S. Macon Attorney, Agent orFirm0strolenk, Faber Gerb & Soffen l l ABSTRACT A pair of contacts foruse in a high voltage gas blast circuit interrupter each consists oftubular members having one solid end, with the opposite end of thecontacts being segmented to define contact fingers. One contact is fixedand the end of its segmented fingers receive the solid end of themovable contact. The operating shaft for moving the movable contact tothe open position is then connected to the movable contact through aspring member to cause a time delay between the initial openingoperation of the operating shift and the opening ofa blast valve alsooperated by the operating shaft before the movable Contact is snapped toan open position with respect to the stationary contact.

8 Claims, 4 Drawing Figures PATENTEDJUN 10 1915 men.

SHEET I CONTACT FOR HIGH VOLTAGE GAS BLAST CIRCUIT BREAKER WITHTIME-DELAYED OPENING RELATED APPLICATIONS This application is related tocopending application Ser. Nos. 398,871, filed Sept. l9, I973, entitledCONTACT STRUCTURE FOR HIGH VOLTAGE GAS BLAST CIRCUIT INTERRUPTER, in thename of H. Aumayer; 398,869, filed Sept. l9, I973, entitled MECHANICALSUPPORT OF TRANSIENT RE- COVERY VOLTAGE CAPACITOR WITHIN CIR- CUITBREAKER LOW PRESSURE TANK, in the name of L. D. McConnell, and 398,868,filed Sept. 19, I973, entitled GAS CIRCUIT BREAKER INSULAT- ING TUBESUPPORT AND HIGH PRESSURE VES- SEL, in the name of G. P. Guaglione etal., all of which are assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates to a novel contactstructure for gas blast circuit interrupters, and more specificallyrelates to a novel contact structure which is easy to manufacture andwhich provides a time delay following the opening of a blast valve andthe opening of the circuit breaker contacts to ensure the presence andflow of interrupting gas before the contacts open.

Circuit breakers are well known in the art in which a pair of contactsare open in the presence of a blast of gas such as sulfur hexafluoridewhich assists in extinguishing the arc drawn between the contacts.Devices of this type are shown, for example, in U.S. Pat. No. 3,526,734,issued Sept. 1, 1970, entitled DEAD TANK GAS BLAST CIRCUIT BREAKER WITHINTER- RUPTER STRUCTURE IMMERSED IN LOW PRES- SURE OF DEAD TANK, in thename of D. H. McKeough, and in copending application Ser. No. 175,507,filed Aug. 27, 1971, now U.S. Pat. No. 3,823,289, entitled INTERRUPTERSTRUCTURE FOR CIRCUIT BREAKER WITH INDIVIDUAL BLAST VALVES ANDTIME-DELAYED UP- STREAM CUTOFF VALVE, in the name of L. D. Mc Connell et211., both of which are assigned to the assignee of the presentinvention. In these devices, as well as in the device of the presentinvention, the movable contact operating shaft and the blast valve whichadmits high pressure gas such as SP into the arcing area when the valveopens are operated from the same oper ating shaft.

It is known that it is desirable to open the blast valve slightly beforethe contacts are opened so that a gas blast is established before thecontacts initially open so that gas is present at the time of initialcontact arcing. Prior mechanisms to accomplish this initial gas blasthave, however, been very complex and required the use of numerous parts.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the presentinvention, a relatively simple lost-motion mechanical device isconnected between the movable contact and the operating shaft which isalso connected to the blast valve. This then creates a delay or deadtime" in the separation of the arcing contacts to allow time to build uppressure of arc extinguishing gas in the contact region before thecontacts separate. This dead time is obtained through the use of a resetspring which is compressed with the initial opening movement of theoperating shaft, whereby the blast valve opens but the arcing contactsremain closed for some fixed time. The spring then reaches a point whereit exerts sufficient force on the movable contact to overcome thefriction between a segmented movable contact and a stationary support sothat the contacts will snap open to initiate the arcing process. At thesame time, the opening movement of the Contact also opens a relativelylarge passage to permit the high pressure gas to move downstream and extinguish the arc. The opening movement of the arcing contact alsooperates to reset the spring biasing mechanism and operating rod so thatit is in condition for the breaker to be reclosed and ready for a newoperation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of acircuit breaker which employs the novel contacts of the presentinvention where a portion of the grounded support tank of the circuitbreaker has been removed to expose the various components therein.

FIG. 2 is a cross-sectional view through one of the interrupters of thecircuit breaker of FIG. 1 and illustrates the novel contact structure ofthe present invention.

FIG. 2a is a top plan view of the stationary contact of FIG. 2.

FIG. 2b is a side plan view of the movable contact of FIG. 2.

DETAILED DESCRIPTION OF THE DRAWINGS Referring first to FIG. 1, there isshown. in partial section, one phase of a high voltage circuit breakerwhich incorporates the present invention, as will be later described.The circuit breaker of FIG. 1 can, for example, be rated at 230,000volts and at 63,000 amperes. Conventionally, the breaker will be athreephase breaker and two other and identical phases to the one shownin FIG. 1 will also be provided.

In general, the circuit breaker phase of FIG. 1 is contained within agenerally flattened spherical metallic tank 10 which is supported onmetallic frame angle members 11 and I2. Angles I1 and 12 are suitablyreinforced and extend rearwardly and support additional tanks to tank10, which are spaced from the tank 10 and disposed generally parallel totank 10 and constitute the other phases of the circuit breaker. Themetallic tank 10 is a grounded housing and the circuit breaker shownherein for purposes of illustrating the invention is shown in a deadtank configuration.

The terminal bushings for the breaker may be of any standard type andare shown for illustration herein as including the bushings l3 and 14which extend through cylindrical shrouds l5 and 16, respectively, whichare appropriately welded or otherwise secured to the tank 10 and aresealed relative to the interior of the tank. Gas barriers l7 and 18,respectively, are provided to prevent the leakage of gas from tank 10.Thus, tank 10 is filled with sulfur hexafluoride gas (or a gas mixturewhich includes sulfur hexafluoride) at a pressure of about 3atmospheres. For purposes of the invention, any dielectric gas at anyappropriate pressure could be used. For the embodiment described herein,the gas pressure within tank 10 will be designated a relatively lowpressure.

Each of the bushings l3 and I4 is further associated with currenttransformers l9 and 20. respectively. which may also be of any desiredconstruction.

A grounded flat support platform 21 is contained within the tank It) andis supported from the bottom of tank by welded support members. such asbolts 22 and 23 and others not shown. Platform 21 sits on le\el ingnuts. such as nuts 24 and 25. respectively. of the support bolts. Theplatform 21 then serves as a level mount for the circuit interrupterequipment to be contained within tank 10. In the case of the breakershown in FIG. 1, four interrupters are to be connected in series withone another to define the circuit breaker volt age rating of 230 KV.Platform 21 supports two spaced hollow tubular insulation supportmembers 26 and 27, respectively, which further serve the purpose of highpressure gas reservoirs as is more fully described in copendingapplication Ser. No. 398.868, referred to above.

Each of the insulation support members 26 and 27 support. at their tops.respective blast valve housings 28 and 29 which, in turn. supportseries-connected interrupter units 30-31 and 32-33, respectively. Eachof the interrupter units contains a pair of interrupter contacts whichare simultaneously opened in the presence of a blast of gas whichassists in extinguishing the arc. It is to be noted that the tubes 26and 27, blast valve housings 28 and 29. and interrupters 30 to 33 aremechanically supported solely from the platform 21 and that none ofthese components are supported from the bushings 13 and 14 orintermediate supports for the interrupters 31 and 32.

The top of interrupter 30 is electrically connected to the stud 35 ofterminal bushing 13 through a flexible connection, which will be laterdescribed. The connection between the top of interrupter 30 and stud 35is then covered by a corona shield 36.

The bottom of interrupter 30 is then connected through housing 28 to thebottom of interrupter 31. The top of interrupter 31 is connected throughflexible shunts 36a to the top of interrupter 32 with the tops ofinterrupters 31 and 32 and flexible connectors covered by corona shields37 and 38, respectively.

The bottom of interrupter 32 is then connected through the blast valvehousing 29 to the bottom of interrupter 33. The top of interrupter 33 isin turn con nected to the stud 39 of bushing 14 by flexible connectors.such as flexible connectors 40 and 41. The connection previouslyreferred to between interrupter 30 and stud 35 incorporates flexibleconnectors. such as the connectors 40 and 41. The connection to stud 39is then covered by the corona shield 42.

FIG. 1 also shows voltage distributing impedances 43 and 44 connectedacross the interrupters 30 and 33, respectively. Note that any suitablearrangement of parallel-connected capacitors or resistors could be usedacross the various interrupters 30 to 33 in order to assure appropriatedistribution of steady state and transient voltage across theseries-connected breaks.

FIG. 1 illustrates the provision of transient recovery voltagecapacitors and 51 which are to be connected from either of the linesides of the breaker to ground. It will be noted that the flattenedelliptical shape of tank 10 makes available free space in the outercentral regions of the tank so that these capacitors can be mountedwithin this space without interference with the operation of the breakeror without interference with the dielectric integrity of the breaker.The mounting of these capacitors is the subject of copending applicationSer. No. 398.869.

It will be noted from FIG. 1 that the upper terminals ofeach ofcapacitors 50 and 51 are connected by relatively rigid conductors 52 and53 to the tops of interrupters 30 and 33, respectively. and are directlyand solidly connected to the bushing studs 35 and 39. respectively. Thebottoms of capacitors 50 and 51 are then mechanically and electricallyconnected to the tank wall 10 by the support and grounding brackets 54and 55, respectively.

The transient recovery voltage across the breaker is then controlled bythe capacitors 50 and 51 in the manner generally set forth in US. Pat.No. 3,383.5l9. it being noted that each of capacitors 50 and 51 may havea value of approximately 0.0025 microfarads or any other desired valueselected by the circuit designer.

The interior of the insulation reservoirs 26 and 27, which communicatewith the blast valve housings 28 and 29 and thence to the interrupters30 and 33 is at a relatively high pressure, such as 15 atmospheres ofthe same dielectric gas which fills tank 10.

The major pressure source for the breaker is an elongated cylinder 60which is filled with gas at high pressure and which may be covered witha heater blanket 61 to ensure that the gas temperature will always besufficiently high to maintain it in a gaseous state. A protective shroud62 covers the cylinder 60 (which may extend the full length of all ofthe phases of the breaker). with portholes such as porthole 63 beingavailable to permit maintenance of the cylinder 60 and the blanket 61. Asuitable gas control system. which need not be described to understandthe present invention, provides suitable gas conduits and gas controlsto conduit gas from the cylinder 60 through the conduit 64 which passesthrough a sealing plug 65 in tube 66 which is secured to tank 10.

The high pressure conduit 64 then extends through a T-shaped member andinto conduits 67 and 68 as generally outlined by the arrows. in FIG. 1,such that high pressure gas is admitted to the interior of insula tionreservoirs 26 and 27. As will be later described, this gas is normallysealed at the blast valve housings 28 and 29 and high pressure gas isreleased through the interrupters 30 and 33 and into low pressure tank10 only when the contacts of the interrupters are operated.

A suitable mechanical operating mechanism (not shown herein) is providedto mechanically actuate crank arms. such as crank arm 70 associated withtube 26, which drive operating rods which extend through the center ofsupport tubes 26 and 27 and upwardly to blast valve housings 28 and 29.Similar crank arms will be associated with each of the otherinterrupters of each phase of the breaker. Any conventional operatingmechanism. such as a spring operated mechanism or hydraulically operatedmechanism is then connected to each of the crank arms so that all blastvalves and contacts can be simultaneously operated to either open orclose all interrupter contacts.

The specific details of one interrupter structure. such as theinterrupter 30 of FIG. 1 and a portion of the blast valve housing 28,are shown in FIG. 2. Referring now to FIG. 2, the interrupter and blastvalve are shown in cross-section and at the top of FIG. 2. As will belater described, interrupters 30 to 33 are subassembled units which canbe easily installed when the breaker is assembled. Thus, FlG. 2 showstwo flexible shunts S0 and 81 which have upper connectors 82 and 83which are appropriately bolted to the stud 35 of bushing 13, while theother ends of shunts 80 and 81 are bolted to an upper conductive adaptermember 84 of the interrupter 40. Note that the stud 35 does not serve asa mechanical support for the interrupter components.

The upper adapter 84 is bolted to a second adapter portion 85 with thetwo components 84 and 85 defining a volume 86 which leads to dischargeports such as the discharge port 87 which is positioned adjacent asimilar port 88 in the shield 36. Note the position of port 88 in FIG.1.

Additional ports are distributed around the periphery of shield 36 whichlead to similar openings defined between adapter members 84 and 85. Twofurther ports of this general type are shown in FIG. 1 for shield 42 asthe ports 89 and 90.

The adapter member 84 further serves to threadably receive a tubulararcing terminal 91. Note that arcing terminal 91 has an opening 911!therethrough which extends upwardly so that some are venting can bedirectly vertically upward along the axis of the opening in arcingterminal 91.

The use of flexible shunts to make the connection from the top ofinterrupter 30 to the terminal bushing stud 35 is made possible sincethe entire mass of inter rupter structure 30 is supported on top of theblast valve housing 28. In prior art arrangements, such as thearrangement shown in U.S. Pat. No. 3,526,734, the stationary contactstructure of the interrupter is rigidly fastened to and carried by theend of the terminal bushing. This structure required careful alignmentof the in terrupter components during assembly of the breaker and duringits operation. The structure shown in FIG. 2 eliminates the need foralignment during assembly of the circuit breaker and simple flexibleshunt members 80 and 81 are used to connect the top of the preassembledinterrupter 30 to the terminal bushing stud 35. Similar advantages applyto the connection between the top of interrupter 33 of FIG. 1 and theterminal bushing stud 39.

As previously described in connection with FIG. 1 the tops ofinterrupters 31 and 32 are connected in series by the flexible shunt360. This is to be contrasted to the prior art arrangement of US. Pat.No, 3,526,734 which required a separate support insulator extending fromthe top of the housing which would physically carry the stationarycontacts for interrupters 31 and 32. By supporting interrupters 31 and32 from the blast valve housings 28 and 29. the separate supportinsulator and the alignment problems which were caused by the separatemounting of the stationary contacts of these interrupters areeliminated.

The interrupter 30 of FIG. 2 contains an elongated, generally tubularstationary contact member 100 which has an upper solid ring-shaped end101 and slots which form segmented contact fingers, such as fingers 102and 103 in its other end. The segmented fingers of contact 100 are alsoshown in FIG. 2a which is a top end view of the contact 100. It will befurther noted that the ends of the segmented contacts. such as segmentedfinger contacts 102 and 103 terminate with arcing contact inserts whichmay have been formed as an insert ring which was brazed to the tubularcontact member before the tubular member was slotted to form thesegmented finger.

FIG. 20 further illustrates openings such as opening 104 in the solidflange 101 which accepts the bolts. such as bolt 105 which secures thestationary contact to adapter member 85. The bolts which pass throughthe openings in flange 10] of stationary contact 100 are threaded into aconductive ring which clamps the end side of flange 101 against adaptermember 85. Ring 110 serves as an upper support for the insulation tube111 which is the interrupter housing tube. Tube lll may be made of anydesired material. such as an epoxy reinforced glass tube or the like.The upper end of tube 111 is suitably secured to and sealed with respectto ring 110 as by the securing key 112 and sealing ring 113.

A set of bolt openings is formed in the inner diameter of ring 110 andthese bolt openings receive bolts, such as bolt 120, which threadablyengage ring member 121 and hold it in position. The exterior lowerportion of ring 121 is threaded and threadably receives the insulationbaffle 122 which may be ofa suitable arc-resistant material such asTeflon, and serves as a guide for blast gases during the openingoperation of the interrupter, and as a means to protect or shield tube11] from the hot gases created during arc interruption. Baffle 122 alsocontains a plurality ofthin, axially directed and circumferentiallyspaced fins, such as fin 123. These fins then prevent the formation of avortex in the gas blast which is guided by baffle 122.

The lower end ofinsulation tube 111 is fixed in a conductive supportring and is fixed therein and sealed thereto as by the key 131 andsealing ring 132. The ring 130 is, in turn, secured to a spider plate133 as by bolts, such as bolt 134, where the spider plate is formed of aconductive disk 134a having radially extending web sections such assections 135 and 136 which are joined to a centrally extending hollowconductive shaft 137. The shaft 137 then slidably receives the segmentedmovable contact 138 which is slidably engaged with the outer surface ofshaft 137.

The movable contact 138 consists of a generally tubularly shaped memberhaving a solid ring-shaped end 139 which receives a solid arcing ring[40, with the lower end of contact 138 being segmented to form separatecontact fingers, such as fingers 141 and 142.

FIG. 2b show a side plan view of the movable contact 138. The segmentedfinger elements 138 and 142 along with other similar fingers are flexedoutwardly from their normal relaxed position, and are therefor biasedinwardly and into sliding engagement with the outer surface of shaft137. The solid upper end 139 of movable contact 138 is movable into andout of engagement with the segmented fingers. such as fingers 102 and103 of stationary contact 100. When the segmented fingers 102 and 103engage the contact 100, they are elastically flexed outwardly toinherently provide contact pressure to form a good low resistancecontact.

It will be noted, during Contact operation, that the baffle 122 willlead high pressure gas up from the annular volume which surroundsmovable contact 138 and into the baffle 122 and then between theseparating contacts 138 and 100. The gas will also flow in twodirections through the are, both through the center of stationarycontact 100 and the opening in arc terminal 91, and through the centralopening in contact 138 shown as opening 15!.

The movable contact 138 is connected to an operating shaft 152 (whichcontains the opening 151] and the upper end of shaft 152 is providedwith a flange 153. The flange 153 is engageable with the rear surface154 of the movable contact I38 and also receives a compression spring155. The compression spring 155 is seated at its bottom on a ledge 156of a spring retaining cylinder 157 which is threadably secured withinthe upper end of contact 138. The bottom of cylinder 157 slides withinthe interior of conductive tube 137 and slides on a seal 158 within theshaft 137. The operation of the interrupter contacts described abovewill be later described after the blast valve arrangement and support ofthe interrupter from the blast valve housing 28 is described.

As is shown in FIG. 1, the blast valve housing 28 supports bothinterrupters 30 and 31. One lateral half of the blast valve housing 28is shown in FIG. 2 insofar as it relates to the support of interrupter30. It will be noted. however, that the blast valve housing 28 issymmetric so that the same structure shown in connection withinterrupter 30 is provided on the opposite side of the center line 200in FIG. 2 for the support and operation of interrupter 31.

The insulation support member 26 of FIG. 1 is partly shown in FIG. 2 andit is seen that a metal end cap 201 is fitted over and sealed to the topof insulation tube 26. The metal cap 201 then serves as the support forthe conductive support casting 202 of the blast valve hous ing 26.Casting 202 is provided with a slot 203 therein for passing an arm 204which is appropriately con nected to the operating shaft 152 by theadapter fitting 205.

Cap 201 further serves to support ring 210 and circumferentiallydistributed posts such as posts 211 which are welded to ring 210. Theposts 211 are then welded to a valve seat plate 212 which carries thecutoff valve ring 213 of the blast valve as will be later described. Thevalve ring 213 is then held in position by a clamp 214 which is clampedinto engagement with ring 213 by bolts such as bolt 215.

The main operating rod 220, which extends from the crank 70 of FIG. 1then extends through plate 212 and clamping member 214 (in sealedrelation therewith) and is connected to radiating arms, such as arm 221of the blast valve sleeve 222. Note that sleeve 222 also carries theoperating arm 204.

The upper end of blast valve sleeve 222 is engageable with upper blastvalve seal 230 which is clamped in po sition by the clamping plate 2310.The ring-shaped valve seal 230 is carried on plate 231 which isgenerally supported by a ring 232 which is an integral portion of thecasting 202.

The main blast valve sleeve 222 extends downwardly and is threadablysecured to ring-shaped member 240 which has an outwardly projectingflange 241. Flange 241 is engageable with a shoulder 242 on an auxiliarysliding sleeve 243. Note that suitable sliding seals 244 and 245 sealthese sliding surfaces against pressure loss of high pressure gas whichis in the interior of cap 20].

it is now possible generally to describe the operation of theinterrupter and blast valve of FIG. 2. With the components in theposition shown. the interrupter is closed and a current path is formedfrom terminal bushing stud 35 through the flange shunts 80 and 81 andinto the adapter members 84 and 85 and the stationary contact 100. Thecurrent then transfers from stationary contact 100 into the movablecontact 138 and the contact fingers 141 and 142 and into the conductivetube 137. From the conductive shaft 137 the current passes throughcasting 202 and then to interfi rupter 31 which is also supported on theblast valve housing 28. The current then proceeds through theinterrupters 31, 32 and 33 in the same manner and exits at bushing 14.

While the breaker is closed. the high pressure gas It) from within theinsulating support tube 26 fills the volume defined by the annular opengap between the bottom seal 213 and sleeve 243 and upwardly withinsleeve 222 and up to the valve seat 230. The interior of interrupter 30is at the relatively low pressure of the interior of tank 10, ascontrasted to the high pressure which is held at the valve seat 230.

In order to open the circuit breaker, the circuit breaker operatingmechanism (not shown) is actuated to cause all of the operating rods,such as operating rod 220 to move simultaneously. The downward movementof rod 220 causes the sleeve 222 to move downwardly thereby to open theseal between the upper end of sleeve 222 and the valve seat 230. Thispermits the high pressure gas within sleeve 222 to move into the chamberwhich contains spider members 135 and 136 and upwardly through theannular channel 150 within the insulation tube 111. Thus, the pressurewithin the annular volume 150 begins immediately to increase.

At the same time, the downward movement of sleeve 222 causes the shaft152 to move downwardly and, initially, the upper flanged end 153 ofshaft 152 will cause the spring 155 to begin to compress. Thisintroduces an increasing downward force on the seal sleeve 157 and thuson the movable contact 138 which is connected to sleeve 157. Initially,however, the contact 138 does not move since the frictional forcesbetween the segmented fingers, such as fingers 141 and 142 of themovable contact against the outer surface of shaft 137 and thefrictional force between upper contact end 139 and the segmentedcontacts of the stationary contact 100 are sufficiently high to preventcontact motion. Ultimately, however, the spring force becomessufficiently high as to drive the movable contact 138 downwardly,thereby causing the separation of the contact 138 from the segmentedfingers of the stationary contact 100 with a snap action. Note thateventually the flange 153 will pick up shoulder 260 of sleeve 157 if themovable contact does not begin to move under the force of thecompression spring 155 alone.

As the contact tip 140 separates from the arcing contact finger portionsof the segmented stationary contact 100, an arc is drawn between them.Substantial gas pressure has already been established within chamber 150and high pressure gas may begin to flow between the separating contactseven prior to inception of the arc as when the contact separation issomewhat delayed by the lost motion connection between shaft 152 and themovable contact 138.

As the contacts 100 and 138 separate, sulfur hexafluoride or a similarinterrupting gas passes rapidly through the annular region of contactseparation with a portion of the gas flowing onto channel 151 andanother portion of the gas flowing upwardly and through the centralopening in arc terminal 91. The majority of the gas, however, is blastedinto the interior of tank 10 through openings in the shield 36 such asthe port 88 in FIG. 2.

As the contact separate. the upper arc root will seat on the arcterminal 91 and the lower arc root will extend from the arcing tip 140.The arc is quickly cxtinguished under the influence of the rapidlymoving sulfur hexafluoride gas.

At the time the arc is extinguished. the sleeve 222 has movedsufficiently downward so that the shoulder 26] in the outside of thesleeve 262 has picked up the lower sleeve 243 so that the sleeve 243 ismoved downwardly and into engagement with valve seat 213. This operationthen cuts off the further flow of high pressure gas from the interior ofcap 201 toward the interrupter. thereby to conserve the high pressuregas in the reservoir.

In order to reclosc the breaker. the operating rod 220 is moved upwardlyso that the contact operating rod 152 moves upwardly to reclose thecontacts. Little or no gas blast is necessary during the closingoperation. Therefore. there is a time delay in the re-opening of theblast valve. Thus. the sleeve 243 remains scaled against seal 213 untilsleeve 222 and its outwardly facing extension 24] mm c to a sufficientlyhigh position that extension 24] engages the shoulder 242 of sleeve 243.At this point. the lower valve seat 213 is opened so that gas can flowfor the very short time until the upper end of sleeve 222 seats againstseal 230.

An important advantage of the contact structure described above is thatthe contact structure has few parts and no separate contact biasingsprings. Thus. the contact arrangement is inexpensi c and reliable.Moreover. it has been found that by arranging the contacts so that thesegmented contact fingers extend from solid tubular ends for bothcontact 100 and contact 138. a shock wave is not transmitted through themoving contact fingers I38 and H2 at the time ofcontact separation.Therefore. there is no bouncing of the segmented contact fingers 138 and142 on the outer surface of conductive shaft 137 so that there is noburning at this surface which burning would cause a high contactresistance.

A further advantage of the structure of FIG. 2 is that a time delaystructure is easily built into the movable contact of the segmentedcontact configuration to ensure that gas blast action has started beforethe contacts separate.

A further advantage of the contact configuration shown is that. when thecontacts open. the nozzle area for allowing rapid flow of gas fromannular region 150 is snapped open with the opening of the contacts.thereby allowing an extremely large passage for the flow of highpressure gas immediately after contact separation.

Although this invention has been described with respect to its preferredembodiments. it should be understood that many variations andmodifications will now be obvious to those skilled in the art. and it ispreferred. therefore. that the scope oftbc invention be limited not bythe specific disclosure herein. but only by the appended claims.

lhc embodiment of the invention in which an exclusive property orprivilege is claimed are defined as fol lows:

I. In a circuit interrupter.

a generally tubular stationary contact. one end of said generallytubular contact being segmented in an axial direction to define agenerally circular Clllslcl of contact fingers.

(ill

a generally tubular movable contact movable into and out of engagementwith said stationary contact. one end of said generally tubular movablecontact being segmented in an axial direction to define a generallycircular cluster of contact fingers. the opposite end of said movablecontact being a generally solid ring;

said tubular stationary and movable contacts being coaxial; said solidring end of said movable contact being movable into engagement withsurfaces of said circular cluster of contact fingers of said stationarycontact and having a diameter different than the diameter defined bysaid surfaces of said cluster of stationary contact fingers when theyare unflexed. thereby to create a given contact pressure when saidmovable and stationary contacts are in engagement;

and a generally stationary conductive tube supported in insulatedrelation with respect to said stationary contact.

said tubular movable contact being coaxial with respect to saidstationary conductive tube and being in sliding contact engagementtherewith: said segmented movable contact fingers engaging a surface ofsaid conductive tube; said conductive tube having a diameter differentthan the diameter defined by the engaging surfaces of said movablecontact fingers when they are unflexcd. thereby to create a givencontact pressure when said movable contact slides relative to saidconductive tube;

a longitudinally movable o erating shaft connected to said tubularmovable contact and being movable along the axis of said tubular movablecontact to move said movable contact into and out ofengagement with saidstationary contact:

a lost-motion connection means for connecting said operating shaft tosaid movable contact:

and gas blast means operatively connected to said operating shaft andoperable for producing a blast of gas between said stationary andmovable contacts during their movement to a disengaged position;

and wherein said lost-motion connection means delays the time at whichsaid movable contact moves to said disengaged position until after saidgas blast means produces a blast of gas whereby increased gas pressureis established in the region of engagement of said movable andstationary contacts before said contacts are opened.

2. In the circuit interrupter ofclaim I wherein the interior of saidstationary contact and of said movable contact are permanently connectedto a relatively low pressure region. whereby gas flows from the exteriorof said stationary and movable contacts through the interiors thereof tosaid low pressure region during the op eration of said movable contactto a disengaged position relative to said stationary contact.

3. In the circuit interrupter of claim I wherein said lost-motionconnection means includes spring means which is flexed to a biasedcondition in response to opening movement of said operating shaft.thereby to apply an increasing opening biasing force on said movablecontact which eventually snaps said movable contact to its saiddisengaged position.

4. In the circuit interrupter of claim 3 which further includes atubular spring retainer means which concentrically surrounds saidoperating shaft and which is slidably mounted on said conductive tube:one end of said retainer means being fixed to said movable contact; saidspring means having one end thereof connected to said operating shaftand its other end connected to said spring retainer means 5. In thecircuit interrupter of claim 4 wherein said spring retainer means isdisposed concentrically with and between said operating shaft and saidconductive tube.

6. in a circuit interrupter:

a generally tubular stationary contact;

a generally tubular movable contact movable into and out of engagementwith said stationary Contact;

said tubular stationary and movable contacts being coaxial;

and a generally stationary conductive tube supported in insulatedrelation with respect to said stationary contact;

said tubular movable contact being coaxial with re spect to saidstationary conductive tube and being in sliding contact engagementtherewith;

a longitudinally movable operating shaft connected to said tubularmovable contact and being movable along the axis of said tubular movablecontact to move said movable contact into and out of engagement withsaid stationary Contact.

gas blast valve means connected to said longitudil2 nally movableoperating shaft and operable to produce a blast of gas through saidstationary and movable contacts in response to the movement of saidoperating shaft to move said movable contact out of engagement with saidstationary contact; and a lost-motion connetion means for connectingsaid operating shaft to said movable Contact. whereby said lost-motionconnection means delays the time at which said movable contact moves tosaid disengaged position until after said gas blast means produces ablast of gas. whereby increased gas pressure is established in theregion of engagement of said movable and stationary contacts before saidcontacts are opened. 7. In the circuit interrupter of claim 6 whichfurther includes a tubular spring retainer means which concentricallysurrounds said operating shaft and which is slidably mounted on saidconductive tube; one end of said retainer means being fixed to saidmovable contact; said spring means having one end thereof connected tosaid operating shaft and its other end connected to said spring retainermeans.

8. In the circuit interrupter of claim 7 wherein said spring retainermeans is disposed concentrically with and between said operating shaftand said conductive tube.

1. In a circuit interrupter; a generally tubular stationary contact, oneend of said generally tubular contact being segmented in an axialdirection to define a generally circular cluster of contact fingers; agenerally tubular movable contact movable into and out of engagementwith said stationary contact, one end of said generally tubular movablecontact being segmented in an axial direction to define a generallycircular cluster of contact fingers, the opposite end of said movablecontact Being a generally solid ring; said tubular stationary andmovable contacts being coaxial; said solid ring end of said movablecontact being movable into engagement with surfaces of said circularcluster of contact fingers of said stationary contact and having adiameter different than the diameter defined by said surfaces of saidcluster of stationary contact fingers when they are unflexed, thereby tocreate a given contact pressure when said movable and stationarycontacts are in engagement; and a generally stationary conductive tubesupported in insulated relation with respect to said stationary contact;said tubular movable contact being coaxial with respect to saidstationary conductive tube and being in sliding contact engagementtherewith; said segmented movable contact fingers engaging a surface ofsaid conductive tube; said conductive tube having a diameter differentthan the diameter defined by the engaging surfaces of said movablecontact fingers when they are unflexed, thereby to create a givencontact pressure when said movable contact slides relative to saidconductive tube; a longitudinally movable operating shaft connected tosaid tubular movable contact and being movable along the axis of saidtubular movable contact to move said movable contact into and out ofengagement with said stationary contact; a lost-motion connection meansfor connecting said operating shaft to said movable contact; and gasblast means operatively connected to said operating shaft and operablefor producing a blast of gas between said stationary and movablecontacts during their movement to a disengaged position; and whereinsaid lost-motion connection means delays the time at which said movablecontact moves to said disengaged position until after said gas blastmeans produces a blast of gas whereby increased gas pressure isestablished in the region of engagement of said movable and stationarycontacts before said contacts are opened.
 2. In the circuit interrupterof claim 1 wherein the interior of said stationary contact and of saidmovable contact are permanently connected to a relatively low pressureregion, whereby gas flows from the exterior of said stationary andmovable contacts through the interiors thereof to said low pressureregion during the operation of said movable contact to a disengagedposition relative to said stationary contact.
 3. In the circuitinterrupter of claim 1 wherein said lost-motion connection meansincludes spring means which is flexed to a biased condition in responseto opening movement of said operating shaft, thereby to apply anincreasing opening biasing force on said movable contact whicheventually snaps said movable contact to its said disengaged position.4. In the circuit interrupter of claim 3 which further includes atubular spring retainer means which concentrically surrounds saidoperating shaft and which is slidably mounted on said conductive tube;one end of said retainer means being fixed to said movable contact; saidspring means having one end thereof connected to said operating shaftand its other end connected to said spring retainer means.
 5. In thecircuit interrupter of claim 4 wherein said spring retainer means isdisposed concentrically with and between said operating shaft and saidconductive tube.
 6. In a circuit interrupter: a generally tubularstationary contact; a generally tubular movable contact movable into andout of engagement with said stationary contact; said tubular stationaryand movable contacts being coaxial; and a generally stationaryconductive tube supported in insulated relation with respect to saidstationary contact; said tubular movable contact being coaxial withrespect to said stationary conductive tube and being in sliding contactengagement therewith; a longitudinally movable operating shaft connectedto said tubular movable contact and being movable along the axis of saidtubular movable contact to move said movaBle contact into and out ofengagement with said stationary contact; gas blast valve means connectedto said longitudinally movable operating shaft and operable to produce ablast of gas through said stationary and movable contacts in response tothe movement of said operating shaft to move said movable contact out ofengagement with said stationary contact; and a lost-motion connetionmeans for connecting said operating shaft to said movable contact,whereby said lost-motion connection means delays the time at which saidmovable contact moves to said disengaged position until after said gasblast means produces a blast of gas, whereby increased gas pressure isestablished in the region of engagement of said movable and stationarycontacts before said contacts are opened.
 7. In the circuit interrupterof claim 6 which further includes a tubular spring retainer means whichconcentrically surrounds said operating shaft and which is slidablymounted on said conductive tube; one end of said retainer means beingfixed to said movable contact; said spring means having one end thereofconnected to said operating shaft and its other end connected to saidspring retainer means.
 8. In the circuit interrupter of claim 7 whereinsaid spring retainer means is disposed concentrically with and betweensaid operating shaft and said conductive tube.